Mobile base



FIG. 1 is a top perspective view of a mobile base showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image of FIG. 3;

FIG. 4 is a side elevational view of the right hand side thereof, the left hand side view being a mirror image of FIG. 4; and,

FIG. 5 is a bottom plan view of my mobile base. 

The ornamental design for a mobile base, as shown and described. 